I've paid for a second hand canon 70-200mm f4L USM from MPB and it will complete my collection of lenses with a multiplier.
The 1.4x should be sufficient but I noticed a new 2x MK III.
Also I was planning on getting the HOYA HD UV0 at considerably less than the price of the filter I use on my Tamron because I don't believe the Canon lens is brilliant with lens flare anyhow, so I won't be pointing it at the sun.
Is Hoya HD as good as they say?
I cannot stop down beyond f7.1 or don't want to, is the new 2x MK III worth considering since I was thinking more sport than wildlife, aircraft rather than birds,